Generally, rerolling is not worth the effort. It can take hours and sometimes days to get something you are satisfied with.

But, I did reroll because I was certain that I wanted a specific unit. Getting that first copy did make my early game progression more enjoyable.

It took me the better part of a day to get the unit, but this was mostly passive time waiting for the game to reinstall. This was roughly 20 full attempts.

The only was to speed up the process, that I am aware of, is to install lite version. You can change the quality later. If you are willing to spend some time clearing some of the story, you can get more orbs quickly. However, this will get boring very quickly.